Analysis of transcriptional levels of the oxytocin receptor in different areas of the central nervous system and behaviors in high and low licking rats

Rat dams exposed repeatedly to a daily brief separation from the pups exhibit increased maternal behavior, decreased anxiety and altered levels of receptors for estrogens (ERα, ERβ), oxytocin and serotonin (5-HT1A) in their brain

“…Our results are in agreement with those of Francis et al (1999) who demonstrated lower levels of anxiety in high LG-ABN females. In contrast to our findings -and those of Francis et al (1999) -, Ruthschilling et al (2012 report that high and low LG mothers, which differ in the expression of maternal behavior, did not show differences in their behavior in the EPM. The discrepancy with our data, showing reduced levels of anxiety in our experimental dams (the equivalent of high LG mothers) could result from differences in the experimental protocols utilized: For instance Ruthschilling et al, assess anxiety on PND8 while we do so on PND12 and PND22.…”

“…Our results extend those of previous studies using natural variations in maternal care, in which analogous changes have been reported for the hypothalamic and extended amygdalar areas, as well as the lateral septum (Francis et al, 2000;Champagne et al, 2001Champagne et al, , 2003Ruthschilling et al, 2012). Relevantly, expression of maternal behavior is accompanied by activation of neurons in the amygdala, MPOA, and SL, preferentially those containing ER␣ receptors (Fleming and Walsh, 1994;Lonstein et al, 2000).…”

“…In our model of enhanced maternal care, both types of ERs as well as oxytocin receptors are increased in many limbic system areas (PFC, the hippocampus, CeA, SL, MPOA and nAc-Sh), implicated in the control of maternal behavior (Numan et al, 1977;Fleming et al, 1980Fleming et al, , 1983Ehret and Buckenmaier, 1994;Fleming and Walsh, 1994;Numan and Sheehan, 1997;Sheehan and Numan, 2002;Stack et al, 2002;Li and Fleming, 2003a,b;Afonso et al, 2007;Numan et al, 2010;Ruthschilling et al, 2012). Our results extend those of previous studies using natural variations in maternal care, in which analogous changes have been reported for the hypothalamic and extended amygdalar areas, as well as the lateral septum (Francis et al, 2000;Champagne et al, 2001Champagne et al, , 2003Ruthschilling et al, 2012).…”

“…Relevantly, expression of maternal behavior is accompanied by activation of neurons in the amygdala, MPOA, and SL, preferentially those containing ER␣ receptors (Fleming and Walsh, 1994;Lonstein et al, 2000). Furthermore, our work draws attention to the role of the hippocampus in the control of maternal behavior, a topic for which existing information is sparse (Ehret and Buckenmaier, 1994;Ruthschilling et al, 2012). The localization of the increase of ERs and OTRs in the shell of the nAc, shown herein, is in agreement with previous reports that blocking of nAc shell OTRs inhibits consolidation of maternal memory (D'Cunha et al, 2011), which is important for the expression of maternal behavior.…”

“…Based on the above, we hypothesized that an experimental manipulation which alters maternal care, would do so by inducing changes in the levels of ER␣ and ER␤ as well as OTRs and 5-HT1ARs in limbic system areas, i.e. the prefrontal cortex-PFC, hippocampus, medial preoptic area-MPOA, lateral septum-SL, shell of nucleus accumbens-nAc-Sh and amygdala (central-CeA and basolateral-BLA nuclei), which are known to participate in the network controlling the expression of maternal behavior (for reviews see Numan and Sheehan, 1997;Pereira and Morrell, 2011;Ruthschilling et al, 2012). Increased maternal behavior in the experimental group of dams was induced by subjecting them to a repeated brief separation (15 min daily) from their pups on postnatal days 1 to 22, as in the ''neonatal handling'' protocol (Levine, 1957).…”